The present invention relates to a control system for a hybrid system comprising at least one energy store and an energy source, the control system using a charge state in the at least one energy store, a nominal operating point of the energy source and a system power which is currently to be output to ascertain a storage power which is to be output or received by the at least one energy store and a source power which is to be output by the energy source on the basis of at least one optimization criterion.
Such a control system is known from DE 196 24 252 A1. DE 195 05 726 A1 and DE 43 41 817 A1 also disclose similar control systems for a hybrid system. Depending on the configuration and design of the energy store and the energy source, the power ratio between the two may fluctuate. In all cases, however, the energy source is an internal combustion engine having a coupled generator, and the energy store is a battery.
In the prior art, control systems for hybrid systems are always designed specifically for the respective hybrid system. Hence, a dedicated control system is formed for each hybrid system.
DE 29 52 500 C2 discloses a control unit which can be used to select one of a plurality of subsections of a store. In particular, the control unit can be used in an on-board computer for motor vehicles.
The object of the present invention is to create a control system which can be used universally for a multiplicity of hybrid systems. In particular, the aim is to create a control system which is not stipulated for a specific combination of a particular energy store with a particular energy source. By way of example, the aim is for the at least one energy store to be able to be a battery, a supercapacitor or a flywheel. The energy source is intended to be capable of being an internal combustion engine having a coupled generator, or a fuel cell or an overhead line, for example. The power ratio between the energy store and the energy source is also intended to be capable of fluctuating significantly, e.g. between 15:85 and 85:15.
The object is achieved by virtue of the fact that at least one charge limit value and at least one discharge limit value for the at least one energy store and a power limit value for the energy source are also used at the same time in order to ascertain the storage power and the source power, and that the at least one charge limit value, the at least one discharge limit value, the power limit value and the nominal operating point can be parameterized via an interface in the control system.
The control system is even more flexible if an energy store charge limit value provided on the basis of the at least one energy store and an input charge limit value which can be input are prescribed to the control system as charge limit values.
The control system is also more flexible if an energy store discharge limit value provided on the basis of the at least one energy store and an input discharge limit value which can be input are prescribed to the control system as discharge limit values.
The flexibility of the control system is increased still further if the at least one optimization criterion can be prescribed via the interface in the control system.
The control response of the control system is optimized still further if the control system uses the charge state of the at least one energy store to ascertain a state charge limit value, a state discharge limit value and a source charge power on the basis of power characteristic values for the at least one energy store, the power characteristic values comprise at least one minimum energy content and a maximum energy content and the power characteristic values can also be prescribed via the interface in the control system.
The energy store is optimally utilized if the control system uses the charge state of the at least one energy store to ascertain a critical system power to be output at which the energy store is changed over from energy absorption to energy output and vice versa.
If the critical system power is subject to hysteresis, constant changeover between charging and discharging is prevented.
If the control system uses the power limit value and the nominal operating point to ascertain whether there is a changeover from energy absorption to energy output when the critical system power is exceeded or undershot, the user of the control system does not need to parameterize the latter.
The charge state of the at least one energy store is optimized still further if the critical system power is corrected if the charge state of the energy store falls below the minimum energy content or exceeds the maximum energy content.
Excessive changes in the source power are prevented if the storage power is supplied to an adder via a ramp as first input signal, the second input signal supplied to said adder being the system power which is to be output, and the output signal which is output is the source power.